In an oil and gas production operation, hydrocarbon fluid is produced with multiphase flows. These flows can include oil, gas, and water. The amount of water in the produced fluid can be referred to as the water cut of the fluid. The water cut of the produced fluid is closely monitored to determine operational parameters such as oil/water contact level and water breakthrough. Accurate measurement of the water cut is thus important to the oil and gas production operation. The water cut measurement can also be referred to as on-line water determination.